Solid-state lighting is an attractive alternative to incandescent and fluorescent lighting systems for a wide range of applications because of its relatively higher efficiency, robustness, and long life. In many cases, the long operational life of LEDs permits installation into systems such as fixtures, housings, or extrusions without provision for changing the LED source(s), because the LED lifetime exceeds the expected system lifetime. In many applications it is desired to minimize the size and/or volume of such systems. However, conventional LED systems typically require some form of heat-sinking or thermal management that is difficult to incorporate, particularly in relatively small and enclosed spaces. This is a particular issue for systems formed within a housing or extrusion. In such cases, the housing or extrusion typically must be large enough to accommodate not only the LEDs, circuit boards, and any heat sinks, but also must be engineered to not overheat from heat generated by the LEDs during operation. Such constraints may require additional ventilation, for example, passive ventilation or active ventilation such as fans, to prevent deleterious heat buildup. These issues typically lead to undesirably large, thick, and potentially complicated lighting systems.
In some applications it may be desirable for the housing of an LED-based lighting system to provide additional functionality, for example to aid in light distribution control, e.g., by using optics to achieve a specific light distribution pattern. For example, cove lighting or wall wash lighting systems often include a housing incorporating optics to achieve the desired light distribution patterns. The size and complexity of the optical elements are related to the size of the light source and the desired light distribution pattern, in many cases leading again to undesirably large systems.
In some applications the housing may provide protection for the LEDs, for example mechanical protection (e.g., protection against an object hitting or crushing the lighting system) or protection from environmental factors such as water, rain, snow, or the like. Outdoor applications typically require a housing for physical and environmental protection of the LEDs and associated circuitry. Such housings are often undesirably large because of the need to enclose the LEDs, circuit board, heat sinks, and associated control and drive circuitry.
Finally, many applications for backlighting and illuminated panels and signs require custom sizing to fit in a particular location. Systems featuring relatively few high-brightness LEDs on rigid circuit boards may be difficult to use cost-effectively in a wide range of installations while achieving high illumination uniformity and high efficiency.
Accordingly there is a need for solutions that provide LED-based lighting systems having a small form factor, provide the desired light distribution pattern, and which are simple to install.